The present invention relates generally to test systems for IC (integrated circuit) packages, and more particularly, to a low maintenance design of an IC package test handler having a chilled water jacket for controlling the temperature at the IC package.
During manufacture of IC (integrated circuit) packages, the IC packages are tested for proper functionality, as known to one of ordinary skill in the art of IC package manufacture. Referring to FIG. 1A, an IC package test handler 100 of the prior art holds an IC package 102 to a test station such that a plurality of leads, including a first lead 104, a second lead 106, a third lead 108, a fourth lead 110, and a fifth lead 112, contact a socket of the test station, as known to one of ordinary skill in the art of IC package manufacture. An IC package typically has more numerous leads in an array of leads, but five leads 104, 106, 108, 110, and 112 are shown in FIG. 1A for clarity of illustration. The IC package test handler 100 includes a sponge 114 for sealing in a vacuum suction for holding the IC package 102.
During testing of the IC package 102 at the socket of the test station, the integrated circuit within the IC package 102 dissipates power during operation, and the IC package 102 heats up. However, during testing of the IC package 102, a predetermined temperature may be desired at the IC package 102. In addition, with excessive heating of the IC package 102, the testing circuitry of the test station may be damaged.
Thus, the IC package test handler 100 includes a heating element 116 for heating the IC package 102 and a chilled water jacket 118 for cooling the IC package 102. The chilled water jacket 118 is filled with chilled water that is circulated through the chilled water jacket 118. Chilled water flows into the chilled water jacket 118 through a chilled water inlet hose 120. Water becomes heated within the chilled water jacket 118, and this heated water is disposed out from the chilled water jacket 118 through a heated water outlet hose 122 such that chilled water constantly circulates through the chilled water jacket 118.
The chilled water jacket 118 is disposed within a test handler housing 124 which is comprised of aluminum in the prior art IC package test handler 100. The heating element 116 is embedded within a test handler base 126 of the test handler housing 124, and the test handler base 126 is integral with the test handler housing 124 in the prior art IC package test handler 100. A temperature sensor 128 is also embedded within the test handler base 126.
A first extension spring is comprised of a first extension spring portion 130 and a second extension spring portion 131. Referring to FIGS. 1A and 1B, the first extension spring portion 130 is wound around a first screw 132, and the second extension spring portion 131 is wound around a second screw 133. The portion of the first extension spring between the first extension spring portion 130 and the second extension spring portion 131 is wound around a first hose fitting 134. The first hose fitting 134 is disposed within the chilled water inlet hose 120 for directing chilled water into the chilled water jacket 118.
A second extension spring is comprised of a third extension spring portion 135 and a fourth extension spring portion 136. Referring to FIGS. 1A and 1C, the third extension spring portion 135 is wound around a third screw 137, and the fourth extension spring portion 136 is wound around a fourth screw 138. The portion of the second extension spring between the third extension spring portion 135 and the fourth extension spring portion 136 is wound around a second hose fitting 139. The second hose fitting 139 is disposed within the heated water outlet hose 122 for directing heated water out of the chilled water jacket 118. The first hose fitting 134 and the second hose fitting 139 are coupled to the chilled water jacket 118 and support the chilled water jacket 118.
In the prior art IC package test handler 100, an extending membrane 142 is stretched over the chilled water jacket 118. A compressed air inlet 144 provides compressed air above the extending membrane 142 such that the extending membrane 142 extends down to push down the chilled water jacket 118.
During operation of the prior art IC package test handler 100, when the temperature at the IC package 102 as sensed by the temperature sensor 128 is below a desired temperature, the amount of compressed air through the compressed air inlet 144 is decreased such that the extending membrane 142 is retracted back and not pushing down the chilled water jacket 118. In that case, the chilled water jacket 118 does not contact the test handler base 126. In addition, for raising the temperature at the IC package 102 to the desired temperature, the heating element 116 embedded in the test handler base 126 is turned on to heat up the test handler base 126. The heated test handler base 126 which contacts the IC package 102 in turn heats up the IC package 102.
On the other hand, referring to FIG. 2, when the temperature at the IC package 102 as sensed by the temperature sensor 128 is above a desired temperature, the amount of compressed air through the compressed air inlet 144 is increased such that the extending membrane 142 extends down to push down the chilled water jacket 118 to contact the test handler base 126. The chilled test handler base 126 which contacts the IC package 102 in turn cools down the IC package 102. In addition, for lowering the temperature at the IC package 102 to the desired temperature, the heating element 116 embedded in the test handler base 126 is turned off.
In this manner, the temperature at the IC package 102 is controlled using feedback control. However, the prior art IC package test handler 100 may require highly skilled labor and cost for maintenance. For example, the extending membrane 142 is stretched uniformly across the test handler housing 124 for proper operation of the IC package test handler 100. If the extending membrane 142 has a loose area, then the compressed air may further extend only that loose area of the extending membrane 142 such that the chilled water jacket 118 is not uniformly pushed down properly onto the test handler base 126.
In addition, because the test handler housing 124 of the prior art is comprised of aluminum, heat is transferred easily through the test handler housing 124, and the heating element 116 does not efficiently heat up the test handler base 126. Furthermore, when the heating element 116 is heated with current flowing through the heating element 116, when the insulating material surrounding the heating element 116 wears down, the heating element 116 may electrically short with the test handler housing 124 comprised of aluminum such that the heating element 116 no longer functions properly.
Additionally, because the test handler base 126 is integral with the test handler housing 124, when a component of the test handler base 126 is inoperative, the whole IC package test handler 100 is dismantled to fix the test handler base 126. Such a process is time-consuming, and renders the whole IC package test handler 100 inoperative while the test handler base 126 is being fixed.
Also, the first extension spring portion 130, the second extension spring portion 131, the third extension spring portion 135, and the fourth extension spring portion 136 are extended and wound around the screws 132, 133, 137, and 138 and around the hose fittings 134 and 139 with a proper amount of extension force for proper operation of the IC package test handler 100 of the prior art. The extension spring portions 130, 131, 135, and 136 are extended with a proper amount of extension force such that the chilled water jacket 118 does not contact the test handler base 126 when the extending membrane 142 is not extending down and such that the chilled water jacket 118 does contact the test handler base when the extending membrane 142 is extending down.
If the extension spring portions 130, 131, 135, and 136 are extended with an improper amount of extension force, the chilled water jacket 118 may not be supported properly. For example, if the extension spring portions 130, 131, 135, and 136 are extended with too much extension force, portions of the chilled water jacket 118 may improperly not contact the test handler base 126 when the extending membrane 142 is extending down. On the other hand, if the extension springs portions 130, 131, 135, and 136 are extended with too little extension force, portions of the chilled water jacket 118 may improperly contact the test handler base 126 when the extending membrane is not extending down. In addition, the extension springs portions 130, 131, 135, and 136 are extended uniformly such that the chilled water jacket 118 is supported evenly for proper operation of the IC package test handler 100 of the prior art. Thus, skilled labor may be required for proper installation of the extension springs in the IC package test handler 100 of the prior art.
Thus, a design of an IC package test handler for minimized maintenance is desired.
Accordingly, in a general aspect of the present invention, an IC package test handler, for holding an IC package to a socket of an IC package test station, is designed for minimized maintenance.
In one embodiment of the present invention, the IC package test handler includes a test handler housing for caring a chilled water jacket. The test handler housing is comprised of a thermal insulating material, and chilled water circulates through the chilled water jacket. A test handler base cartridge is mounted to a bottom of the test handler housing, and the test handler base cartridge contacts the IC package when the IC package test handler is holding the IC package to the socket of the IC package test station. The test handler base cartridge is comprised of a thermally conductive material. The test handler base cartridge includes a heating element embedded within the test handler base cartridge for heating up the test handler base cartridge. The test handler base cartridge also includes a temperature sensor embedded in the test handler base cartridge, and the temperature sensor contacts the IC package to sense a temperature at the IC package when the IC package test handler is holding the IC package to the socket of the IC package test station.
A cylinder piston is disposed on top of the chilled water jacket, and compressed air from a compressed air source is provided to the cylinder piston such that the cylinder piston pushes the chilled water jacket down toward the test handler base cartridge. An IC package temperature controller is coupled to the temperature sensor, the heating element within the test handler base cartridge, and the compressed air source. The temperature controller controls the compressed air source to decrease an amount of the compressed air provided to the cylinder piston to retract the cylinder piston away from the chilled water jacket such that the chilled water jacket does not contact the test handler base cartridge, and controls the heating element to heat up the test handler base cartridge, to increase the temperature of the IC package when the temperature at the IC package as sensed by the temperature sensor is below a desired temperature. Alternatively, the temperature controller controls the compressed air source to increase an amount of the compressed air provided to the cylinder piston to extend she cylinder piston toward the chilled water jacket such that the chilled water jacket contacts the test handler base cartridge, and controls the heating element to turn off, to decrease the temperature of the IC package when the temperature at the IC package as sensed by the temperature sensor is above the desired temperature.
In this manner, a cylinder piston is used instead of the extending membrane for pushing down the chilled water jacket against the test handler base cartridge. The cylinder piston simply may be dropped into a cavity for proper operation of the IC package test handler. In addition, because the test handler housing is comprised of a thermally insulating material which does not readily conduct heat, the heating element within the test handler base cartridge efficiently heals up the IC package.
The present invention may be used to particular advantage when the test handler base cartridge is coupled to the bottom of the test handler housing by a plurality of screws. Thus, the test handler base cartridge is replaceable by another test handler base cartridge that may be on-hand such that the IC package test handler may be used while a faulty test handler base cartridge is being fixed.
Furthermore, a plurality of compression springs are disposed within the test handler housing and disposed below the chilled water jacket. The compression springs are compressed down when the chilled water jacket is pushed down by the cylinder piston toward the test handler base cartridge, and the compression springs push the chilled water jacket back up away from the test handler base cartridge when the cylinder piston retracts away from the chilled water jacket. These compression springs are simply dropped into cavities internal to the test handler housing.
These and other features and advantages of the present invention will be better understood by considering the following detailed description of the invention which is presented with the attached drawings.